The Boeing Company

Duke University

Sun Microsystems, Inc.

Research Triangle Institute

Kishor S Trivedi

Yun Liu

David W Twigg

Anapathur V Ramesh

Tilak C Sharma

Dazhi Wang

Le P Nguyen

Kenny C Gross

Fengmin Gong

Feiyi Wang

Kalyanaraman Vaidyanathan

Katerina Goseva-Popstojanova

Rong Wang

Balamurugan Muthusamy

Xiaomin Ma

Dongyan Chen

Yiguang Hong

A computer-based method for determining a probability that no path exists from a starting node to a target node within a network of nodes and directional links between pairs of nodes. The nodes and directional links form paths of a reliability graph and the method is performed using a computer coupled to a database. The method includes selecting a set of paths between the starting node and the target node that have been determined to be reliable, calculating a reliability of the union of the selected path sets, setting an upper bound for unreliability of the set of all paths, selecting a set of minimal cutsets from all cutsets that lie between the starting node and the target node, calculating the probability of the union of the minimal cutsets, and setting a lower bound for the unreliability of the set of all cutsets.

Reliability estimation methods for large networked systems

A computer-based method for determining a probability that no path exists from a specified starting node to a specified target node within a network of nodes and directional links between pairs of nodes is described. The nodes and directional links form paths of a reliability graph and the method is performed using a computer coupled to a database that includes data relating to the nodes and the directional links The method includes selecting a set of paths, from the set of all paths, between the starting node and the target node that have been determined to be reliable, calculating a reliability of the union of the selected path sets, setting an upper bound for the unreliability of the set of all paths, based on the calculated reliability, selecting a set of minimal cutsets from all such cutsets that lie between the starting node and the target node, calculating the probability of the union of the minimal cutsets, and setting a lower bound for the unreliability of the set of all cutsets.

An intrusion tolerant communication network and related methods is provided that places emphasis on continuity of operation and provides for an attack-survivable communication network whose network devices collectively accomplish the specified networking intent even under attack and despite active intrusions. The present invention defines methods for network intrusion tolerance in terms of the various state transitions that maximize the overall effectiveness of an intrusion tolerant communication network.

Intrusion tolerant communication networks and associated methods

One embodiment of the present invention provides a system that facilitates using a multi-variate pattern-recognition technique to trigger software rejuvenation for a computer system. The system operates by periodically measuring values of a target set of performance parameters associated with the computer system while the computer system is operating. The system then predicts values for the target set of performance parameters based upon previously determined correlations between performance parameters in the target set of performance parameters. If the predicted values deviate beyond a predetermined threshold from the measured values, thereby indicating that software aging is likely to have occurred, the system schedules a software rejuvenation operation for the computer system.

Method and apparatus for using pattern-recognition to trigger software rejuvenation

Methods and systems for improving utilization of traffic channels in a mobile communications network. A method for allocating communication channels is provided for allocating communication channels for handoff in a first base station having a communication link with active mobile stations located in a handoff area of the first base station and a second base station. The method includes constructing a channel convertible set including communication channels for active mobile stations moving in a direction away from the first base station; receiving a handoff request from a requesting mobile station having a communication link with the second base station; and determining whether a free channel is available for the handoff request. Furthermore, the method includes allocating one of the communication channels in the channel convertible set to the handoff request if a free channel is not available for the handoff request.

Methods and systems for improving utilization of traffic channels in a mobile communications network

Methods and Systems for Determining an Optimal Training Interval in a Communications System. A method is provided for determining an optimal training interval for a channel of a communications system. The method can include a step for receiving first channel estimations of a signal carried by a channel of a communications system, wherein the first channel estimations are generated by a first channel estimator. The communications system can include a normal mode for utilizing the channel to carry user data, a training mode for training the first channel estimator, and a failure mode for recovering channel communication after channel failure. The method can include a step for determining a time distribution of the channel transition from the normal mode to the failure mode, wherein channel failure occurs when error in the first channel estimations exceeds a first predetermined threshold. Further, the method can include a step for applying Markovian analysis to the time distribution of the channel transition to determine a first training interval such that channel utilization in the normal mode is maximized.

Methods and systems for determining an optimal training interval in a communications system

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Durham, NC, United States of America

Kishor S Trivedi